Track roller assembly

ABSTRACT

A track roller assembly including a track roller having axially aligned axle shafts rotatably mounted within end caps which are securable to the track frame of a crawler tractor. Each end cap is provided with a bearing assembly which includes a sleeve-type bushing and a disc-type washer which respectively serve to absorb radial and thrust loads. The inner circumferential bearing surface of the bushing is partially relieved at points adjacent the opposite edges of the bushing so as to prevent binding of the axle shafts due to misalignment between the axle shafts and the end caps.

United States Patent [1 Story et al.

[4 1 Nov. 20, 1973 [22] Filed:

[ TRACK ROLLER ASSEMBLY [75] Inventors: Thomas A. Story,Aurora; Peter B.

Cadou, Shaker Heights, both of Ohio [73] Assignee: General Motors Corporation,

' Detroit, Mich.

Sept. 20, 1972 [21] Appl. No.: 290,462

[52] U.S. Cl 305/14, 305/28, 308/18 [51] Int. Cl B62d 55/14 [58] Field of Search 305/14, 28; 308/18 [56] I References Cited UNITED STATES PATENTS 1,796,533 3/1931 Pearson 305/28 X 3,116,957 1/1964 Fikse 305/14 2,827,339 3/1958 Zunich 308/18 2,823,079 2/ 1958 Williams 305/14 7 1774 22 as 54 8t 3,088,782 5/1963 Conlan 305/28 X FOREIGN PATENTS OR APPLICATIONS 925,572 3/1955 Germany 305/14 Primary Examiner-Richard .1. Johnson Att0meyWi1liam S. Pettigrew et a1.

[5 7] ABSTRACT A track roller assembly including a track roller having axially aligned axle shafts rotatably mounted within end caps which are securable to the track frame of a crawler tractor. Each end cap is provided with a bearing assembly which includes a sleeve-type bushing and a disc-type washer which respectively serve to absorb radial and thrust loads. The inner circumferential bearing surface of the bushing is partially relieved at points adjacent the opposite edges of the bushing so as to prevent binding of the axle shafts due to misalignment between the axle shafts and the end caps.

4 Claims, 8 Drawing Figures I PATENIEDHDVBOIBB 3773,3915 1 sum 10; 3

PATENHEDrmvzo ms SHEET 2 UF 3 I TRACK ROLLER ASSEMBLY This invention concerns track roller assemblies for tracked vehicles such as crawler tractors. As is" well known; the usual crawler tractor includes a main tractor chassis and. longitudinally extending track frames which are connected to the opposite sides of the chassis.- The track frames support the endless tracks of the vehiclegandare formed by a-pair of laterally spaced longitudinally extending frame members or rails. A plural ity. of track roller assemblies are mounted: inlongitudinall'y spaced relation along each track frame. for rolling contact with the ground engaging portionof the endless tracks, and: each roller assembly usually: includes aLroller body rotatablysupported-from end: caps or support members at the opposite ends thereof whichare rigidly secured to the frame members of the track'frame. The support means for the roller body take various forms but: inevitably include either sleeve-typebearings or roller bearings used for reducing friction and wear. The

sleeve-type: bearings: or. bushings havecertain.- advantages over roller bearings inthatthey are lessexpensive and: require less-space, however, because the'friction area is quite large, damaging. heatcan-'result ifiadequatej lubrication: is not providedi As is well known; heatbuildupats times is quickly'followed by'scorihgof both the bushing and the: shaft resulting in a: worn bUSIIIIi'gwhich willnot hold the shaftfsin proper alignment Kccordingly, the ideahtype of bushing arrangement v for a'; track roller shoul'dbe. one in which thetlirust bushing isplacediin a position" where it can provide maximum thrust-iareaand atthe sametime obtain'sufi'leient liib'ri catibnso'asto .prolbng the life of the bushing; Als'mthe thrust 'bushingjshouldbepositioned:so astoexperiencei a'mini'mun i amount ofsurface speeds 'while-b'eing' capable ofs'erv'ing asa=heat dissipatorofany heat induction as" a:. result ofthrust loading; In' addition; the radial bushing should be so designed as toen'su'r'e against binding which might result from= ihitiali misalignment and deflections whichmightoceur under' load;

This: invention contemplates a track roller which meets thes above requirements by havinga roller body formedwith a pa'ir of: axially aligned axle.-sl1afts' rigidly secured thereto and & projecting from r the opposite ends thereof. Each of: the axle shafts has-a I cylindrical o'uter surface and an'endsurtace whichliesin aplane perpen dicularto the-longitudinal center axis-ofthe axle shafts.

A pair of laterallyxspaced end "caps receive the respective axle shaftsandserve to-supportthem'for:rotation within a dead end bore which isdefined-bya cylindrical inner wallyfand an endi wall. A bearing-iassembly ismounted the bore and interposed 'betweemthe end cap and the axle-shaftand includes asleeve-typecylim minimum-"surface'speeds.

" The objects of :the present invention are to' providea track rollenassembly 'of tlfe live shaft 1 type utilizing? sleeve-type' bushing which is partially relieved adjacent P the opposed edges thereof so as to com pensate for mis cured within a cylindrical bore'form'ed in'end caps. 1 5* alignment between a roller axle shaft and mounting; to provide a live shaft track roller in which each int'egral axle shaft is carried within an end cap having as'leeve; type bushing for absorbing the radial loads anda dish} type washer for absorbing thrust loads; to provide a track roller assembly for a crawler tractor that rotat ably supported steam endby a sleeve-type bushing and disc-type thrust washer which are provided suitable channels for allowing lubric ant to flow wear surfaces for minimizing frictional wear thereof; and'to provide'a bearing assembly I the stub shafts of a live shaft track roller that includes asle'ev e-jtype bushing and a thrust washer, both of which are f xedly sewhich are mountable to the track frame of a crawler tractor. I I I Gther objects and advantages of the present invention will be apparent from the following detailed description whentaken with the drawings in which:

FIG. 1* is aside elevational' view of a crawlertractor equipped with a plurality 'of track roller assemblies made according to this invention; 7

FIG'., 2 is an isometric iview showing a sleeve-type bushing incorporated with each track roller assembly of FIG. 1; t 7

FIG. 3' is an enlarged'view taken on line 3 3 of FIG. I

FIG-1 4 is a-view taken on line 4'4 of FIG. 3; FIGS. 5 and6 are enlarged'sectional views taken on lines5"-5;and 6-6of FIG. 4; and r FIGS. 7"and-8 are cross-sectionalviews taken on lines 7--' 7 and 8'--8'of FIG. 3:

' Referring to the drawings and more particularly FIG.

I thereof, a crawler tractor lfl'is'shown which'includes the usuallongitudinally extending track frame 12 located'on-each side of the vehicle. In thiscase, the track frame Plan the leftside of the vehicle is shown only and as seen" in FIG. 3; each track frame 12 includes rigid interconnected and'laterally spaced frame mem- 'bers or rails I4 and l6. The forward end of each trackthrough a suitable engine and gear train (not shown) for propelling'th'e vehicle in a manner well known in the art. The groundengagingportion 24 of each endless-track intermediate the idler and sprocket wheels is engaged and supported by a plurality of live shaft track aligned'stub axle shafts 30*and32 which project outwardly. from the-opposite'en'dsof the roller body. 28.

The axleshafts 30 and 32 jare rotatably supported by a frame 12. Each end cap 34 and 36 fixedly supports a bearihgassem'bly-which is interposed between the axle sh aft and'its associated end cap so asto provide substantially'frictionless'rotation of the track roller'assembly; Thebearing assembly in"'each'end cap' 34 and 36 is identical in construction and includes a sleeve-type bearing or bushing 38 and a disc-type thrust washer 40, both of which cooperate for absorbing and transferring loads imposed on the roller both radially and axially thereof. 7

Each end cap 34 and 36 is formed with a dead-end bore defined by a cylindrical inner wall 42 and an end wall 44. As seen in FIGS. 3 and 4, the end wall 44 has a vertically extending channel 46 formed therein which is adapted to receive a liquid lubricant such as oil which is introduced into. e roller assembly through a port 48 which in this case is closed by a threaded plug 50. The channel 46 connects with a longitudinally extending groove 52 formed in the lower portion of inner wall 42 that serves to allow the lubricant to flow to bushing 38 and also to a suitable seal means 53 interposed between the inboard end of the end cap and the roller body.

It will be noted that the end wall 44 serves as a flat support for the thrust washer 40 which is centered in the bore by a pair of recessed dowels 54 and 55 as seen in FIGS. 4 and 5. It will also be noted that the flat outer wear face of the thrust washer 40 is divided into four pie-shaped sections 56, 58, 60, 62 by two pairs of axially aligned grooves 64, 66, 68 and 70. Each pair of aligned grooves is located along an axis which is perpendicular to the axis of the other pair of aligned grooves. As best seen in FIGS. and 6, the grooves are V-shaped in cross section and serve as channels for the lubricating oil which is conveyed to the wear surface of each of the sections 56, 58, 60 and 62 of the thrust washer 40 by the rotating end surface 72 of each of the stub axle shafts. The end surface 72 in each instance is located in a vertical plane which is parallel to the wear surface on the adjacent thrust washerand the end wall 44. The wear surface of the thrust washer 40 as well as the inner surfaceof the bushing have a bronze coating 74 of twenty to thirty thousandths of an inch which serves as the wear material.

The thrust washer 40 is formed with a centrally located circular opening 76 which is axially aligned with an elongated passage 78 that extends through each axle shaft. As seen in FIG. 3, each passage 78 opens into an enlarged cavity 80 in the roller body 28 that serves as a reservoir for the lubricating oil. Thus, it should be apparent that, in operation, the cavity 80 as well as the passages 78 are completely filled with the lubricating oil which can then flow via the channel 46 and groove 52 to lubricate the seals 53 and'also the wear surfaces of the thrust washer 40 and the bushing 38. I

As seen in FIGS. 2 and 3, the bushing 38 is cylindrical in form and has an inner surface which asafo remen;

tioned is coated with bronze. Intermediate the'outer edges of the bushing an annular groove 82 is formed into the inner surface of the bushing and the groove 82 communicates with an opening 84 that leads to the groove 52. Thus, lubricating oil in the groove 52 can flow via the opening 84 into the groove 82 for lubricating the wear surface of the bushing 38. It will also be noted that adjacent each edge of the bushing is a relieved portion 86 which extends approximately 120 about the inner circumferentialsurface of the bushing. The relieved portions 86 together with the groove therefore define two narrow strips of wear surface which merge with the wear surfaces at the upper end of the bushing as seen in FIG. 3. The relieved portions 86 serve to allow the track roller to rotate without binding in an instance where minor misalignment between the stub axles and the end caps may exist. Moreover, by having the upper portion of the inner-surface of the bushing coated-with bronze as described hereinbefore, a maximum amount vofsunfacearea-is'provided for absorbing the loading, imposed upon the track roller during operation of thecrawler tractoixof FIG. 1.

As mentioned above, one advantageof the track r014- ler assembly 26 is its ability.to operateisatisfactorily. even though there may be some; misalignment oflth'eg stub axles 30 and 32 relative to theend. caps '34 and 36 and also during times whendeflections occur under load. In addition, it will. be noted that by:having the thrust washer 40 formed and positioned as described, a maximum amount of thrust area is provided at points where the surface speed of the end surface 72 is at av minimum since the wear surfaces are located relatively close to the center of rotational axis of the stub axles. ln other words, surfacespeed is directly proportional to the distance from the center of rotation and therefore the further that the wear surfaces are located from the center the higher the surface speed. In this particular design, by having the wear surfaces positioned near to the rotational axis of the stub axles, slower surface speeds are realized with less heat frictional generation and total wear. Another advantage of this design is that heat transfer from the bearing assembly is minimized with the end caps 34 and 36 serving as a means for dissipating heat by-c'onvection to the ambient air surface. 7 Various changes and modifications can be made in this construction without departing from the spirit of the invention. Such changes and modifications are contemplated by the inventor and he does not wish to be limited except by the scope of the appended claims.

I claim: l

l. A track roller assembly adapted to be mounted on a track frame of a tracked vehicle comprising a track roller, a a pair of axially aligned axle shafts rigidly s'ecured to and projecting from the opposite ends of said 1 track roller, each of said axle shafts having a cylindrical outer surface and an end surface lying in a plane perby a cylindrical inner wall and an end wall for receiving and supporting each of said axle shafts for rotation about saidlongitudinal center axis, a bearing assembly mounted in said bore and interposed between the end cap and the axle shaft, said bearing assembly including a sleeve type bushing fixedly supported by said inner wall andihaving a cylindrical inner bearing surface for engaging the outer surface of the axle shaft and absorbing radial loads, and a disc-type washer secured to said end wall and having a flat outer bearing surface located in a plane parallel to said end surface for absorbing thrust loads, said inner bearing surface being partially relieved at the side edges of the bushing so as to prevent binding of said axle shafts in said end caps due to misalignment therebetween.

2. The track roller assembly of claim 1 wherein said inner bearing surface is relieved along an are bounded ing means are provided between said track roller and said end cap inboard of said bearing assembly.

4. A live shaft track roller assembly adapted to be mounted on a crawler tractor track frame having a pair of spaced frame members, said live shaft track roller assembly comprising a track roller disposed between said frame members and having a cavity for storing a liquid lubricant, a pair of axially aligned axle shafts rigidly secured to and projecting from the opposite ends of said track roller, each of said axle shafts having a cylindrical outer surface and an end surface lying in a plane perpendicular to the longitudinal center axis of said axle shafts, a pair of axially aligned end caps rigidly secured to said frame members, each end cap having a bore formed therein defined by acylindrical inner wall and an end wall for receiving and supporting an axle shaft for rotation about said longitudinal center axis, a bearing assembly mounted in said bore and interposed between the end cap and the axle shaft, said bearing assembly including a sleeve type bushing fixedly supported by said inner wall and having a cylindrical inner bearing surface for engaging the cylindrical outer surface of the axle shaft and absorbing radial loads, an annular groove formed in said inner bearing surface intermediate the side edges of the bushing, a disc-type washer secured to said end wall and having a flat outer bearing surface divided into four sections by a pair of grooves located along mutually perpendicular axes, said flat outer bearing surface being located in a plane parallel to said end surface for absorbing thrust loads, the axle shafts having passages formed therein for connecting the cavity with said grooves formed in the bushings and the disc-type washer, the annular groove in inner bearing surface and the grooves in the flat outer bearing surface serving as conduits for allowing the liquid lubricant to flow from said cavity and through said passages to said bearing surfaces, and said inner bearing surface of the bushing being partially relieved at the side edges of the bushing so as to prevent binding of said axle shafts in said end caps due to misalignment therebetween. 

1. A track roller assembly adapted to be mounted on a track frame of a tracked vehicle comprising a track roller, a a pair of axially aligned axle shafts rigidly secured to and projecting from the opposite ends of said track roller, each of said axle shafts having a cylindrical outer surface and an end surface lying in a plane perpendicular to the longitudinal center axis of said axle shafts, an end cap having a bore formed therein defined by a cylindrical inner wall and an end wall for receiving and supporting each of said axle shafts for rotation about said longitudinal center axis, a bearing assembly mounted in said bore and interposed between the end cap and the axle shaft, said bearing assembly including a sleeve type bushing fixedly supported by said inner wall and having a cylindrical inner bearing surface for engaging the outer surface of the axle shaft and absorbing radial loads, and a disc-type washer secured to said end wall and having a flat outer bearing surface located in a plane parallel to said end surface for absorbing thrust loads, said inner bearing surface being partially relieved at the side edges of the bushing so as to prevent binding of said axle shafts in said end caps due to misalignment therebetween.
 2. The track roller assembly of claim 1 wherein said inner bearing surface is relieved along an arc bounded by a pair of radii originating at the center of the bushing and spaced by an angle greater than 90* but less than 180*.
 3. The track roller assembly of claim 1 wherein sealing means are provided between said track roller and said end cap inboard of said bearing assembly.
 4. A live shaft track roller assembly adapted to be mounted on a crawler tractor track frame having a pair of spaced frame members, said live shaft track roller assembly comprising a track roller disposed between said frame members and having a cavity for storing a liquid lubricant, a pair of axially aligned axle shafts rigidly secured to and projecting from the opposite ends of said track roller, each of said axle shafts having a cylindrical outer surface and an end surface lying in a plane perpendicular to the longitudinal center axis of said axle shafts, a pair of axially aligned end caps rigidly secured to said frame members, each end cap having a bore formed therein defined by a cylindrical inner wall and an end wall for receiving and supporting an axle shaft for rotation about said longituDinal center axis, a bearing assembly mounted in said bore and interposed between the end cap and the axle shaft, said bearing assembly including a sleeve type bushing fixedly supported by said inner wall and having a cylindrical inner bearing surface for engaging the cylindrical outer surface of the axle shaft and absorbing radial loads, an annular groove formed in said inner bearing surface intermediate the side edges of the bushing, a disc-type washer secured to said end wall and having a flat outer bearing surface divided into four sections by a pair of grooves located along mutually perpendicular axes, said flat outer bearing surface being located in a plane parallel to said end surface for absorbing thrust loads, the axle shafts having passages formed therein for connecting the cavity with said grooves formed in the bushings and the disc-type washer, the annular groove in inner bearing surface and the grooves in the flat outer bearing surface serving as conduits for allowing the liquid lubricant to flow from said cavity and through said passages to said bearing surfaces, and said inner bearing surface of the bushing being partially relieved at the side edges of the bushing so as to prevent binding of said axle shafts in said end caps due to misalignment therebetween. 